Set the Environment Variables

After installing oneTBB, set the environment variables:

1. Go to the oneTBB installation directory.

2. Set the environment variables using the script in <install_dir> by running:

   • On Linux* OS: vars.{sh|csh} in <install_dir>/tbb/latest/env

   • On Windows* OS: vars.bat in <install_dir>/tbb/latest/env

Build and Run a Sample

Windows* OS

1. Create a new C++ project using your IDE. In this example, Microsoft* Visual Studio* Code is used.

2. Create an example.cpp file in the project.

3. Copy and paste the code below. It is a typical example of a oneTBB algorithm. The sample calculates a sum of all integer numbers from 1 to 100.

   #include <oneapi/tbb.h>
   
   int main (){
       int sum = oneapi::tbb::parallel_reduce(
           oneapi::tbb::blocked_range<int>(1,101), 0,
           [](oneapi::tbb::blocked_range<int> const& r, int init) -> int {
               for (int v = r.begin(); v != r.end(); v++) {
                   init += v;
               }
               return init;
           },
           [](int lhs, int rhs) -> int {
               return lhs + rhs;
           }
       );
   
       printf("Sum: %d\n", sum);
       return 0;
   }

4. Open the tasks.json file in the .vscode directory and paste the following lines to the args array:

   • -Ipath/to/oneTBB/include to add oneTBB include directory.

   • path/to/oneTBB/ to add oneTBB.

   For example:

   {
      "tasks": [
           {
              "label": "build & run",
              "type": "cppbuild",
              "group": {
              "args": [
                  "/IC:\\Program Files (x86)\\Intel\\oneAPI\\tbb\\2022.0.0\\include",
                  "C:\\Program Files (x86)\\Intel\\oneAPI\\tbb\\2022.0.0\\lib\\tbb12.lib"

5. Build the project.

6. Run the example.

7. If oneTBB is configured correctly, the output displays Sum: 5050.

Linux* OS

1. Create an example.cpp file in the project.

2. Copy and paste the code below. It is a typical example of a oneTBB algorithm. The sample calculates a sum of all integer numbers from 1 to 100.

   #include <oneapi/tbb.h>
   
   int main(){
       int sum = oneapi::tbb::parallel_reduce(
           oneapi::tbb::blocked_range<int>(1,101), 0,
           [](oneapi::tbb::blocked_range<int> const& r, int init) -> int {
               for (int v = r.begin(); v != r.end(); v++) {
                   init += v;
               }
               return init;
           },
           [](int lhs, int rhs) -> int {
               return lhs + rhs;
           }
       );
   
       printf("Sum: %d\n", sum);
       return 0;
   }

3. Compile the code using oneTBB. For example,

   g++ -std=c++11 example.cpp -o example -ltbb

4. Run the executable:

   ./example

5. If oneTBB is configured correctly, the output displays Sum: 5050.

Hybrid CPU and NUMA Support

If you need NUMA/Hybrid CPU support in oneTBB, you need to make sure that HWLOC* is installed on your system.

HWLOC* (Hardware Locality) is a library that provides a portable abstraction of the hierarchical topology of modern architectures (NUMA, hybrid CPU systems, etc). oneTBB relies on HWLOC* to identify the underlying topology of the system to optimize thread scheduling and memory allocation.

Without HWLOC*, oneTBB may not take advantage of NUMA/Hybrid CPU support. Therefore, it’s important to make sure that HWLOC* is installed before using oneTBB on such systems.

Check HWLOC* on the System

To check if HWLOC* is already installed on your system, run hwloc-ls:

• For Linux* OS, in the command line.

• For Windows* OS, in the command prompt.

If HWLOC* is installed, the command displays information about the hardware topology of your system. If it is not installed, you receive an error message saying that the command hwloc-ls could not be found.

Install HWLOC*

To install HWLOC*, visit the official Portable Hardware Locality website (https://www-lb.open-mpi.org/projects/hwloc/).

• For Windows* OS, binaries are available for download.

• For Linux* OS, only the source code is provided and binaries should be built.

On Linux* OS, HWLOC* can be also installed with package managers, such as APT*, YUM*, etc. To do so, run: sudo apt install hwloc.